I’m not a diet absolutist or a purist, but if I had to join a diet camp and stay there, it would be with the vegans, and specifically the whole-foods, plant-based vegans. My experience and common sense tell me that this is a good way to eat. There’s some evidence that it’s healthy. There’s a lot of evidence that it’s economically and environmentally sound. Mostly vegetables, fruits, whole grains, nuts and seeds, all that good stuff. I’m for it.

So this week, I watched the much-discussed What the Health, since when my partner’s out of town, all I do is watch documentaries about fitness and stuff. As a person who is personally and professionally invested in health, I wanted to like it. But alas, I was thoroughly disappointed, and even a little pissed off. Yes, I’m late to the party. But whatever. The thing is, I think the overall message is probably right– processed meat is bad for you, industrial production of animal foods creates major health hazards, animal agriculture is an ethical and environmental abomination, and major health advocacy groups take money from corporations that promote unhealthy products, thereby creating a colossal conflict of interest. So why package this message in a bunch of evangelism, cheap tricks, and scientific misrepresentation? It’s bad for the message.

indeed.

Let’s take a moment to discuss crimes against science: no credible scientific paper would ever say something like “this definitely shows beyond the shadow of a doubt that a always causes b no matter what, and this is 100% true beyond the shadow of a doubt.” Science doesn’t work that way. Evidence accumulates– with nuanced approaches and varied findings, and over time, it may start to become clear what’s likely going on. Scientists study the studies and look at patterns and trends. They create meta-analyses and systematic reviews. They build a body of credible evidence. They don’t pull a handful of individual studies out and ask why they haven’t been made into policy.

Then, there’s the problem that it’s easier to study some things than others. Nutrition happens to be notoriously difficult to study. You just can’t isolate the effects of dietary patterns on health long-term– because people eat what they eat, and they do it in the context of their other exposures to environment, exercise, social structure, education, genetics. . . you get the point. So we have a few short-term studies that are more highly controlled (individual nutrients or foods studied in limited time frames), and a few long-term studies that are observational (populations compared to other populations; associations among self-reported eating habits and different health outcomes). That’s it, folks. There’s not a huge body of impeccable, convincing science suggesting that any diet is the best. There is some evidence for the effects of individual diet components on specific outcomes. There’s some evidence of the role of overall dietary patterns, along with other factors, in health and longevity. There are a very few randomized studies of specific dietary patterns (and they’re not perfect!) But in terms of “proof” about a superior diet? Not so much.

So, in What the Health, when Kip goes to meet with an ADA spokesman and waves a study around about the role of meat in causing diabetes, he’s letting is ignorance show. It’s like he’s shouting, “because science, guys! there’s a science about this, I swear!”. The ADA isn’t perfect and they don’t have all the answers, but it’s foolish to suggest gross negligence on their part for failing to promote an approach that is promising but not fully understood by science. The ADA website includes “Meal Planning for Vegetarian Diets” This page includes resources and information, including that some research suggest a vegan diet can prevent and slow diabetes.

So it doesn’t really look to me like they are hiding this information– just that they haven’t hitched their wagon to a promising approach that’s in its infancy in terms of evidence. That is actually responsible, in the greater scheme of things– evidence on diet goes through fads, and staying to a moderate approach, like ADA does, is probably wise. They aren’t going to be nimble and cutting edge. They’re going to be slow and middle-of-the-road. That’s completely appropriate.

But I digress. Back to the crimes against science! Cherry-picking. Ooof. It’s rampant in the movie— a few studies are discussed, but a lot of evidence is ignored. Some of that evidence is equivocal or contradictory to what’s presented, and it isn’t any weaker in design or numbers. Kip is right, there are studies showing benefits of plant-based diets as they relate to diseases like diabetes, but telling a piece of the story is equivocation if not outright dishonesty.

Then we get to the individual stories about people who changed their diet and got healthy. This is fine, but it’s not science. This is more like Fat, Sick, and Nearly Dead. That’s cool– it’s totally fine to show how making certain changes made individuals healthier. But don’t imply that this is in the same category as scientific evidence. Likewise, if some of the physicians in the film have seen good results in patients this way, also great! But it’s still not science. And when the experts interviewed are selling books or programs to lose weight, my confidence starts to slide.

But What the Health wasn’t without merit. The most interesting, and stickiest, claims in the movie are about the financial relationships among big food companies, the government, and patient/consumer health organizations. This isn’t science, it’s politics and economics– and it stinks. Some of this comes up in Salt Sugar Fat (like the check-off programs). There are conflicts of interest everywhere! Big food and animal agriculture industry groups have their tentacles everywhere– the USDA, the AHA, the ADA, the ACS. . . it isn’t good. It’s undeniable that there is influence associated with money, even if it isn’t a clear quid-pro-quo. There sure is a whole lot of smoke if nothing’s on fire. I think Kip buried the lede here and failed to play to his strengths as an investigator and a documentarian. He should stick to this side and leave the science to people who know how to use it.

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One thought on “What happens when a plant-loving scientist watches What the Health”

Great post! Your explanation of how research works is very clear as is your description of how faulty logic weakens the case. I can think of more than a few politicians who could use this basic outline! Write on!